Nr.6009-Chlorine Bleach as a Disinfectant

Of interest is the combination of sodium hypochlorite and Twin Oxides (chlorine dioxide) to increase the quality of swimming pool water. 
In Spain we have  good experiences: 
a) sodium hypochlorite: dosage of 1 ppm instead of 3 ppm 
b) No pH-regulators 
c) Twin Oxide-0,3-dioxide solution: dosage of 0.04 ppm 
W. Storch (www.twinoxide.com)


http://de.wikipedia.org/wiki/Natriumhypochlorit


http://home.howstuffworks.com/bleach2.htm

Chlorine Bleach as a Disinfectant

The use of chlorine bleach as a medical disinfectant was first recorded in Austria in 1847. Staff at the Vienna General Hospital began using it to keep "childbed fever," a severe infection that killed countless women after they gave birth, from spreading throughout the maternity ward [source:American Chemistry Council]. It's now used to disinfect dialysis equipment, some surgical equipment, surfaces in hospitals and medical labs, and even some medical waste [source: Ronco & Mishkin].

The food processing industry uses chlorine bleach to kill hazardous bacteria such as Listeria, Salmonellaand E. coli on equipment. Sodium hypochlorite also is added to municipal drinking water to kill dangerous waterborne organisms like the bacterium Salmonella typhi, which causes typhoid fever and killed many people before water disinfection and antibiotic treatment became common [source: American Chemistry Council].

Chlorine bleach kills Vibrio cholerae, the bacterium that causes cholera, a disease that killed in epidemic proportions before water treatment. It can still kill in countries where clean drinking water is not available. Chlorine bleach can also kill dangerous bacteria and viruses on surfaces, such as methicillin-resistantStaphylococcus aureus (MRSA), influenza and HIV. Chlorine bleach is especially valuable as a disinfectant, since germs are not able to develop immunity against it, as they have done against certain drugs [source:Lenntech].

To kill germs, sodium hypochlorite uses the same quality that makes it such a great stain remover -- its power as an oxidizing agent. When sodium hypochlorite comes in contact with viruses, bacteria, mold or fungi, it oxidizes molecules in the cells of the germs and kills them. Scientists also believe that the hypochlorous acid that forms when sodium hypochlorite is added to water can break down the cell walls of some germs [source: Lenntech]. The hypochlorous acid also seems to be able to cause certain proteins to build up in bacteria, making their cells unable to function [source: Winter]. Non-chlorine bleaches that are oxidizing agents can also act as disinfectants on some surfaces, but they are less potent than chlorine bleach. Chlorine bleach, when used properly, is a practical and effective disinfectant.

Chlorine Bleach for Laundry

Chlorine bleach contains the active ingredient sodium hypochlorite (NaOCl), while non-chlorine bleaches have different active ingredients for different purposes.Hydrogen peroxide, for instance, is common in color-safe bleaches, and sodium percarbonate or sodium perboate are typically used in "oxygen power" stain removers.

So what, exactly, happens to that ketchup stain on your white t-shirt when you bleach it? In order to understand how chlorine bleach makes a stain "disappear," we need to understand how colors work. Light is both a particle and a wave; its particles, called photons, travel in waves that have a particular length. Not all wavelengths of light are visible to the human eye: infrared light wavelengths are too long for our eyes to see, and ultraviolet wavelengths are too short. The wavelengths we can see are between 400 and 700 nanometers, and they appear as color to us. For example, when light with a wavelength of about 475 nanometers hits the retina in your eye, you perceive the color blue. The light that comes from the ketchup stain on your t-shirt to your retina has a wavelength of about 650 nanometers, which makes it appear red [source: Atmospheric Science Data Center].

The reason the ketchup stain reflects light with a wavelength of 650 nanometers has to do with its chemical makeup. Like most other substances, ketchup is made up of multiple elements joined together by chemical bonds to form molecules. The electrons involved in some of these bonds are capable of absorbing light of certain wavelengths, depending on the characteristics of the chemical bond. The light that the electrons in a substance can't absorb determines the substance's color. So the ketchup stain is absorbing all of the wavelengths of normal light that hit it -- except the 650 nanometer light, which it reflects back to your eye, making it appear red.

Many stains have a network of double bonds between carbon atoms, and this network absorbs light. Chlorine bleach is able to oxidize many of these bonds, breaking them and taking away the substance's ability to absorb light. When this happens, the stain "disappears." When bleach oxidizes the ketchup on your T-shirt, the ketchup stops being able to absorb light. It then appears white, like the rest of the shirt. The remains of the ketchup can still be there; you just won't see the stain anymore. Soaking and washing the shirt can remove the now-invisible stain [source: Barrans].

Chlorine Bleach as a Disinfectant

The use of chlorine bleach as a medical disinfectant was first recorded in Austria in 1847. Staff at the Vienna General Hospital began using it to keep "childbed fever," a severe infection that killed countless women after they gave birth, from spreading throughout the maternity ward [source:American Chemistry Council]. It's now used to disinfect dialysis equipment, some surgical equipment, surfaces in hospitals and medical labs, and even some medical waste [source: Ronco & Mishkin].

The food processing industry uses chlorine bleach to kill hazardous bacteria such as Listeria, Salmonellaand E. coli on equipment. Sodium hypochlorite also is added to municipal drinking water to kill dangerous waterborne organisms like the bacterium Salmonella typhi, which causes typhoid fever and killed many people before water disinfection and antibiotic treatment became common [source: American Chemistry Council].

Chlorine bleach kills Vibrio cholerae, the bacterium that causes cholera, a disease that killed in epidemic proportions before water treatment. It can still kill in countries where clean drinking water is not available. Chlorine bleach can also kill dangerous bacteria and viruses on surfaces, such as methicillin-resistantStaphylococcus aureus (MRSA), influenza and HIV. Chlorine bleach is especially valuable as a disinfectant, since germs are not able to develop immunity against it, as they have done against certain drugs [source:Lenntech].

To kill germs, sodium hypochlorite uses the same quality that makes it such a great stain remover -- its power as an oxidizing agent. When sodium hypochlorite comes in contact with viruses, bacteria, mold or fungi, it oxidizes molecules in the cells of the germs and kills them. Scientists also believe that the hypochlorous acid that forms when sodium hypochlorite is added to water can break down the cell walls of some germs [source: Lenntech]. The hypochlorous acid also seems to be able to cause certain proteins to build up in bacteria, making their cells unable to function [source: Winter]. Non-chlorine bleaches that are oxidizing agents can also act as disinfectants on some surfaces, but they are less potent than chlorine bleach. Chlorine bleach, when used properly, is a practical and effective disinfectant.

Environmental Impact of Chlorine Bleach Use

The Environmental Protection Agency (EPA) has evaluated multiple scientific studies on the effects of chlorinated drinking water, and the organization's found no evidence of risk for cancer, reproductive problems or birth defects [source: Environmental Protection Agency]. The European Commission (EC) also determined that the most common sources of exposure to chlorine bleach is through skin contact when using bleach for cleaning at home or through ingestion of chlorinated drinking water. Swallowing small amounts of swimming pool water may also be a risk, but there is no significant indirect exposure through the environment. The Commission determined that there is no evidence of negative health effects due to long-term exposure to small amounts of chlorine bleach [source: European Commission Health & Consumer Protection Directorate-General].

According to the Centers for Disease Control's Agency for Toxic Substances and Disease Registry, when sodium hypochlorite is released into the air, it's broken down by sunlight and natural substances in the environment. Sodium hypochlorite does not accumulate in the food chain like some substances do, such as mercury. When sodium hypochlorite gets into water or soil, it breaks down into the ions sodium, calcium, and hypochlorite; these ions can potentially react with other substances in water, but the possible effects are not known [source: Agency for Toxic Substances and Disease Registry].

In other health issues, bleach may help out. A recent study published in the journal Pediatrics found some improvement in children's eczema after bathing them with a diluted bleach solution; because all of the children in the study also had signs of a secondary bacterial skin infection, however, it's difficult to say whether the bleach helped the eczema or simply killed the infection and helped the skin to heal [source:Huang ].

When it's used properly, chlorine bleach can make your kitchen cleaner and your white clothes whiter. To learn more about bleach, see the links on the next page.

Lots More Information

Related HowStuffWorks Articles

·         Can bleach cure eczema?

·         Why do some clothing items have a tag saying to wash the item before wearing?

·         How Dry Cleaning Works

Sources

·         A Sanitary History of Household Bleach. (2007). Retrieved October 20, 2009, from American Chemistry Council http://www.americanchemistry.com/s_chlorine/sec_content.asp?CID=1166&DID=4482&CTYPEID=109

·         Aftalion, F. (2001). A history of the international chemical industry (2nd Edition ed.). Philadelphia: Chemical Heritage Foundation.

·         Agency for Toxic Substances and Disease Registry. (2007, September 24). Retrieved October 21, 2009, from Department of Health and Human Services http://www.atsdr.cdc.gov/MHMI/mmg184.html

·         Atmospheric Science Data Center. (2007, September 28). Retrieved October 18, 2009, from NASA http://eosweb.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html#blue

·         Chlorine Story. (2007). Retrieved October 21, 2009, from American Chemistry Council http://www.americanchemistry.com/s_chlorine/sec_content.asp?CID=1166&DID=4476&CTYPEID=109

·         Disinfectants sodium hypochlorite. (2009). Retrieved October 21, 2009, from Lenntech http://www.lenntech.com/processes/disinfection/chemical/disinfectants-sodium-hypochlorite.htm

·         Dr. Laundry. (2009). Retrieved October 21, 2009, from The Clorox Company http://www.drlaundryblog.com/

·         Hersman, M. (2003). Mountain State Water Line. West Virgina Rural Water Association.

·         Huang, J. t., Abrams, M., Tlougan, B., Rademaker, A., & Paller, A. S. (20009). reatment of Staphylococcus aureus Colonization in Atopic Dermatitis Decreases Disease Severity. Pediatrics , 123 (5), e808-e814.

·         Integrated Risk Information System: Chlorine. (2009, July 9). Retrieved October 22, 2009, from Environmental Protection Agency http://www.epa.gov/ncea/iris/subst/0405.htm

·         Richard Barrans Jr., P. (2009). Newton Ask a Scientist. Retrieved October 20, 2009, from Argonne National Laboratory http://www.newton.dep.anl.gov/askasci/gen99/gen99486.htm

·         A Sanitary History of Household Bleach. (2007). Retrieved October 20, 2009, from American Chemistry Council http://www.americanchemistry.com/s_chlorine/sec_content.asp?CID=1166&DID=4482&CTYPEID=109

·         Aftalion, F. (2001). A history of the international chemical industry (2nd Edition ed.). Philadelphia: Chemical Heritage Foundation.

·         Agency for Toxic Substances and Disease Registry. (2007, September 24). Retrieved October 21, 2009, from Department of Health and Human Services http://www.atsdr.cdc.gov/MHMI/mmg184.html

·         Atmospheric Science Data Center. (2007, September 28). Retrieved October 18, 2009, from NASA http://eosweb.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html#blue

·         Chlorine Story. (2007). Retrieved October 21, 2009, from American Chemistry Council

·         http://www.americanchemistry.com/s_chlorine/sec_content.asp?CID=1166&DID=4476&CTYPEID=109

·         Disinfectants sodium hypochlorite. (2009). Retrieved October 21, 2009, from Lenntech http://www.lenntech.com/processes/disinfection/chemical/disinfectants-sodium-hypochlorite.htm

·         Dr. Laundry. (2009). Retrieved October 21, 2009, from The Clorox Company http://www.drlaundryblog.com/

·         Hersman, M. (2003). Mountain State Water Line. West Virgina Rural Water Association.

·         Huang, J. t., Abrams, M., Tlougan, B., Rademaker, A., & Paller, A. S. (20009). reatment of Staphylococcus aureus Colonization in Atopic Dermatitis Decreases Disease Severity. Pediatrics , 123 (5), e808-e814.

·         Integrated Risk Information System: Chlorine. (2009, July 9). Retrieved October 22, 2009, from Environmental Protection Agency http://www.epa.gov/ncea/iris/subst/0405.htm

·         Richard Barrans Jr., P. (2009). Newton Ask a Scientist. Retrieved October 20, 2009, from Argonne National Laboratory http://www.newton.dep.anl.gov/askasci/gen99/gen99486.htm

·         Richard Barrans Jr., P. (2009). Newton Ask a Scientist. Retrieved October 19, 2009, from Argonne National Laboratory http://www.newton.dep.anl.gov/askasci/chem99/chem99533.htm

·         Risk assessment report on sodium hypochlorite, human health part. (2008, January 15). Retrieved October 21, 2009, from European Commission Health & Consumer Protection Directorate-General http://ec.europa.eu/health/ph_risk/committees/04_scher/docs/scher_o_080.pdf

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·         Winter, J., Ilbert, M., Graf, P., Özcelik, d., & Jakob, U. (2008). Bleach Activates a Redox-Regulated Chaperone by Oxidative Protein Unfolding. Cell , 135 (4), 691-701.